PROCESS FOR THE CARBONYLATION OF AN ACETYLENICALLY UNSATURATED COMPOUND

Abstract: A process capable of the low temperature carbonylation of an acetylenically unsaturated compound with carbon monoxide in the presence of an allenically unsaturated compound using a catalytic system, which is at least tolerant of the allenically unsaturated compound, formed from a) a palladium compound; b) a protonic acid; c) an organic phosphine of form (I), wherein R<1> is an optionally substituted aryl group; R<2> and R<3> are joined to form an optionally substituted cyclic moiety comprising at least one optionally substituted alkylene group.

Description: Process for the carbonylation of an acetylenically unsaturated compound The invention relates to a process for the carbonylation of an acetylenically unsaturated compound with carbon monoxide in the presence of water an alcohol and/or carboxylic acid It is known that such a compound may be carbonylated with carbon monoxide in the presence of water an alcohol and/or carboxylic acid to yield carboxylic acids esters or anhydrides respectively European Patent EP 0194707 B discloses the hydrocarboxylation of an acetylenically unsaturated compound with carbon monoxide and a carboxylic acid in the liquid phase The reaction is shown to proceed at a temperature of 115°C in the presence of a catalyst system prepared from a palladium (II) compound and a triorganic phosphme, wherein the ratio of the number of moles of triorganic phosphme to gram atom of palladium (II) is greater than 15 The most effective of those triorganic phosphines described in terms of reaction rate is tπphenyl phosphme Published European Patent Application EP 0271144 A discloses the carbonylation of an acetylenically unsaturated compound with carbon monoxide in the presence of a hydroxyl-contaming compound, e g water, an alcohol, a phenol and/or carboxylic acid, in the liquid phase The reaction is shown to proceed at a temperature from 40 to 90°C in the presence of a catalyst system prepared from a palladium (II) compound and a triorganic phosphme compound wherein at least one of the organic groups is a heterocyclic nitrogen containing group, e g pyπdyl One of the most effective of the phosphines described is dιphenyl-2-pyrιdylphosphιne A comparison of the results disclosed in EP 0194707 B with those in EP 0271144 A show that the triorganic phosphme compounds which contain a heterocyclic nitrogen containing group are ten or more times reactive as the previous triorganic compounds, even at lower temperatures A suitable feedstock which contains an acetylenically unsaturated compound may be obtained from the cracking of oil fractions Such a feedstock frequently contains an allenically unsaturated compound in addition to the acetylenically unsaturated compound It is known, however, that an allenically unsaturated compound can have a detrimental effect on the catalyst system as described in EP 0271144 A Consequently, the use of such a catalyst system requires the elimination of any allenically unsaturated compound from the feedstock prior to carbonylation thereof The elimination of the allenically unsaturated compounds requires the use of additional feedstock preparation stages, e g isomeπzation and separation which add to the overall expense and complexity of the conventional carbonylation process It is therefore desirable to dispense with the additional feedstock preparation stages by, for example the use of an alternative more tolerant catalyst system However the other known catalyst systems based on tπphenyl phosphme show such low activity at temperatures below their respective decomposition points under hydrocarbonylation conditions and particularly below 100°C that they cannot be viewed as practical substitutes for the catalyst systems based on pyridyl phosphme It is therefore an object of the present invention to produce a catalyst system which may be of practical use in the carbonylation of an acetylenically unsaturated compound at relatively low temperatures and which catalyst system is at least tolerant to the presence of an allenically unsaturated compound Accordingly, the present invention provides a process capable of the low temperature carbonylation of an acetylenically unsaturated compound with carbon monoxide in the presence of an allenically unsaturated compound and a catalytic system which is capable of catalysing the carbonylation of the acetylenically unsaturated compound and which is at least tolerant of the allenically unsaturated compound, the catalytic system being formed from (a)a palladium compound, (b)a protonic acid (c)an organic phosphme of the form (I) R 1 | R 2 - P - R 3 (I) wherein R 1 is an optionally substituted aryl group, R 2 and R 3 are joined to form an optionally substituted cyclic moiety comprising at least one optionally substituted alkylene group The mechanism through which the catalytic system tolerates the presence of the allenically unsaturated compound and enhances the rate of carbonylation of the acetylenically unsaturated compound is not fully understood However, it is believed that the cyclic moiety may act to provide a source of electrons and/or to regulate the access of unsaturated compounds to the catalyst It is therefore preferred that the cyclic moiety is a relatively rigid structure which contains from 4 to 15, particularly from 6 to 13 and especially from 8 to 1 1 , optionally substituted alkylene groups The phosphorus atom and the cyclic moiety join to form a mono or polycychc structure Thus the organic phosphme is one in which the phosphorus atom forms a link within at least one cyclic group A particularly preferred organic phosphme is one in which the phosphorus atom R 2 and R 3 form a polycyclic group in which the phosphorus atom is a link on a bridge shared by at least two cyclic groups Particularly preferred polycyclic groups include 9-phosphabιcyclo[4,2,1]-nonane and 9-phosphabιcyclo[3,3,1]-noπane Especially preferred is the [4,2,1 ] isomer The group R 1 is an optionally substituted aryl group Preferred groups include anthryl, naphthyl and phenyl all of which may be optionally substituted Particularly preferred is optionally substituted phenyl and especially preferred is phenyl The palladium compound and protonic acid may be any used in EP 0194707 B and EP 0271144 A Suitable combinations employ palladium acetate with a protonic acid such as phenylphosphonic acid or methanesulphonic acid The quantity of palladium compound used can be varied within a wide range Typically a molar ratio from 10 "6 1 to 1 1 , preferably from 10 '5 1 to 1 1 and particularly from 10 "5 1 to 10 "2 1 of palladium to unsaturated compound may be used The quantity of organic phosphme to palladium compound can also vary within a wide range Typically a ratio from 200 1 to 1 1 of organic phosphme to palladium compound may be used The quantity of protonic acid used is not critical and can be varied within a wide range Typically a ratio from 200 1 to 0 1 1 of protonic acid to organic phosphme may be used Suitable acetylenically unsaturated compounds which may be used in the present invention include one or more unsaturated alkyne having from 2 to 20 carbon atoms, for example ethyne, propyne, 1-butyne, 2-butyne, 1-pentyne, 1-hexyne, 1-heptyne, 1-octyne, 2-octyne, 4-octyne, 5-methyl-3-heptyne, 4-propyl-2-pentyne, 1-nonyne, benzylethyne and cyclohexylethyπe The acetylenically unsaturated compound may also be substituted by one or more groups or atoms for example halo, cyano, ester alkoxy, aryl and hydroxy groups Suitable allenically unsaturated compounds which may be used in the present invention include one or more alkadiene having from 3 to 20 carbon atoms, for example propadiene (allene), 1 , 2-butadιene, 1 , 2- pentadiene, 3, 4-octadιene and 3-methyl-1 , 2-butadιene The allenically unsaturated compound may also be substituted by one or more groups or atoms such substituents include halo, cyano, ester, alkoxy, aryl and hydroxy groups The catalyst systems used in the present invention may not only tolerate the presence of allenically unsaturated compounds, but adventitiously may also carbonylate such compounds Thus when R 1 is phenyl and R 2 and R 3 represent the preferred polycyclic groups then such a catalyst system shows a propensity for carbonylatmg allene to methyl methacrylate under the same conditions used for the carbonylation of for example propyne The carbonylation process of the present invention may use any suitable source of hydroxy groups for example water an alcohol or carboxylic acid or mixtures thereof Suitably the hydroxy groups are provided by an alcohol e g methanol The carbonylation process of the present invention may also be conducted in the presence of a suitable solvent Such solvents include anisole and diphenyl ether Other solvents include those disclosed in the prior art acknowledged supra The present catalyst system may be used at elevated temperatures for example from 115°C to 150°C However, the present catalyst system adventitiuosly allows the use of relatively low temperatures as compared to those conventionally employed when triphenylphosphme is used as the organic phosphme compound Typically, therefore, the temperature at which the carbonylation is performed is less than 115°C, preferably less than 100°C for example from 20 to 90°C, and is preferably from 40 and 90°C and especially from 50 to 90°C for example from 50 to 70°C The pressure under which the carbonylation is performed may be selected by the skilled person in order to suit the particular catalyst system used Typically, a total pressure from 5 to 100 bar and in particular from 30 to 80 bar may be used The present invention is illustrated by reference to the following examples EXAMPLE 1 A 1 litre capacity Hastalloy C autoclave was evacuated and then charged with a catalyst solution comprising palladium acetate (0 8 mmol), phosphme ligand (9-phenyl 9-phosphabιcyclo nonane (PPBN) (40 mmol), phenylphosphonic acid (40 mmol), methanol (40 cm 3 ) and anisole (160 cm 3 ) The PPBN used was a mixture of the [3,3 1] and [4,2,1] isomers which were present in the approximate molar ratio of 1 4 Methyl acetylene (30 g) was then introduced and the autoclave pressurised to 60 bar with carbon monoxide and heated to 60°C After set times samples were removed from the autoclave and analysed by gas chromatography for methyl methacrylate EXAMPLE 2 - COMPARATIVE Example 1 was repeated except that tπphenyl phosphme was used as the phosphme ligand instead of PPBN The results of Examples 1 and 2 are shown in Table 1 as the percentage (w/v) of methyl methacrylate detected in the withdrawn samples TABLE 1 LIGAND REACTION TIME (HOURS) 2 24 PPBN 0 5 1 6 Tπphenyl phosphme 0 0 0 4 To further compare the effect of the different ligands the relative rates at which the feedstock was consumed were calculated in terms of moles of feed consumed per mole of palladium per hour (Relative Rate) The Relative Rates obtained from Examples 1 and 2 are shown in Table 1a below TABLE 1a LIGAND REACTION TIME (HOURS) 2 24 PPBN 8 5 7 3 Tnphenyl phosphme 0 0 0 5 It is thus evident that the conventional phosphme ligand is much less active than PPBN under low temperature conditions EXAMPLE 3 Examples 1 and 2 were repeated except that in respect of the PPBN, two experiments were conducted using different amounts of palladium acetate, phenylphosphonic acid and PPBN The amounts of these components were as follows (i) 0 1 g palladium acetate in association with 3 6 g of phenylphosphonic acid and 5 0 g of PPBN and (n) 0 05 g palladium acetate in association with 1 84 g of phenylphosphonic acid and 2 6 g of PPBN In both experiments the results were approximately the same In terms of the Relative Rates the results are as shown in Table 2 TABLE 2 LIGAND REACTION TIME (HOURS) 2 24 PPBN 6 3 5 3 Tnphenyl phosphme 0 0 0 5 EXAMPLE 4 Example 1 was repeated except that the propyne was replaced by allene Also 0 04 g of palladium acetate were used in association 1 36 g of phenylphosphonic acid and 1 9 g of PPBN EXAMPLE 5 - COMPARATIVE Example 4 was repeated except that tnphenyl phosphme was used as the phosphme ligand instead of PPBN Also 0 18 g of palladium acetate were used in association 6 32 g of phenylphosphonic acid and 10 5 g of tnphenyl phosphme At the end of 24 hours palladium metal precipitate was present in the discharged catalyst solution The results of Examples 4 and 5 are shown in Table 3 as the percentage (w/v) of methyl methacrylate detected in the withdrawn samples TABLE 3 LIGAND REACTION TIME (HOURS) 2 24 PPBN 0 1 1 4 Tnphenyl phosphme 0 0 0.5 In terms of Relative Rates the results are as shown in Table 3a TABLE 3a LIGAND REACTION TIME (HOURS) 2 24 PPBN 7 4 6.6 Tnphenyl phosphme 0 0 0 5 It is thus evident that the conventional phosphme ligand is much less active than PPBN in the presence of allene EXAMPLE 6 Example 1 was repeated except that the individual isomers were used instead of a mixture of the isomers Also, different amounts of palladium acetate, phenylphosphonic acid and isomers were used as follows' (i) 0.08 g palladium acetate in association with 3 9 g of phenylphosphonic acid and 4.0 g of [3,3,1] isomer, (ti) 0.09 g palladium acetate in association with 3.07 g of phenylphosphonic acid and 4 3 g of [4,2, 1] isomer; and (in) 0 09 g palladium acetate in association with 3 13 g of phenylphosphonic acid and 4 6 g of [4,2,1] isomer. In both experiments using the [4,2, 1 ] isomer the results were approximately the same In terms of the Relative Rates, the results of the example are shown in Table 4 TABLE 4 LIGAND AFTER 1 HOUR REACTION TIME [3,3.1 ] 10 0 [4,2,1 ] 45 0 EXAMPLE 7 In this example the long term stability of the [4,2,1 ] isomer was assessed in the following manner In a first run the procedure of Example 1 was followed using a catalyst having a formulation of 0 03 g palladium acetate in association with 0 89 g of phenylphosphonic acid and 1 3 g of [4,2, 1 ] isomer After a reaction time of one hour, the entire contents of the autoclave were removed under nitrogen for analysis by gas chromatography The analysis showed the presence of methyl methacrylate methanol and unreacted propyne After removal of voiatiles under reduced pressure a fresh charge of methanol was added and on further analysis the solution was shown to be free from residual methyl methacrylate A second run was then performed in a similar manner to the first run but using the catalyst from the first run instead of fresh catalyst The analysis was repeated at the end of the second run Finally a third run was performed using the catalyst from the second run Again the analysis was repeated The results of the analysis showed that after each run approximately 0 2 % w/v of methyl methacrylate had been formed and that the catalyst had maintained a Relative Rate of 36 EXAMPLE 8 In this example the thermal stability of the [4 2 1] isomer was assessed in the following manner The procedure of Example 1 was repeated using a catalyst having a formulation of 0 04 g palladium acetate in association with 1 73 g of phenylphosphonic acid and 2 3 g of [4 2 1 ] isomer except that the temperature was raised to 90°C Analysis showed that 1 7% w/v of methyl methacrylate was present at the end of the run and that the catalyst had a Relative Rate of 146

Claims: Claims 1 A process capable of the low temperature carbonylation of an acetylenically unsaturated compound with carbon monoxide in the presence of an allenically unsaturated compound and a catalytic system which is capable of catalysing the carbonylation of the acetylenically unsaturated compound and which is at least tolerant of the allenically unsaturated compound the catalytic system being formed from (a)a palladium compound (b)a protonic acid, (c)an organic phosphme of the form (I) R 1 I R 2 - P - R 3 (I) wherein R 1 is an optionally substituted aryl group, R 2 and R 3 are joined to form an optionally substituted cyclic moiety comprising at least one optionally substituted alkylene group 2 A process as claimed in claim 1 wherein the cyclic moiety is a relatively rigid structure which contains from 4 to 15 optionally substituted alkylene groups 3 A process as claimed in either claim 1 or claim 2 wherein the organic phosphme is one in which the phosphorus atom, R 2 and R 3 form a polycyclic group in which the phosphorus atom is a link on a bridge shared by at least two cyclic groups 4 A process as claimed in claim 3 wherein the polycyclic groups are selected from 9-phosphabιcyclo[4,2, 1 ]-nonane and 9-phosphabιcyclo[3,3, 1 ]-nonane 5 A process as claimed in any one of claims 1 to 4 wherein the group R 1 is selected from anthryl, naphthyl and phenyl and substituted analogues thereof 6 A process as claimed in claim 5 wherein the group R 1 is phenyl 7 A process as claimed in any one of claims 1 to 6 wherein the palladium compound is palladium acetate and the protonic acid is phenylphosphonic acid 8 A process as claimed in any one of claims 1 to 7 wherein the quantity of palladium compound used is such that the molar ratio of palladium to unsaturated compound is from 10 "6 1 to 1 1 9 A process as claimed in any one of claims 1 to 8 wherein the quantity of organic phosphme used is such that the molar ratio of organic phosphme to palladium compound is from 200 1 to 1 1 10 A process as claimed in any one of claims 1 to 9 wherein the acetylenically unsaturated compound is one or more unsaturated alkyne having from 2 to 20 carbon atoms 11 A process as claimed in any one of claims 1 to 10 wherein the allenically unsaturated compound is one or more alkadiene having from 3 to 20 carbon atoms 12 A process as claimed in any one of claims 1 to 1 1 wherein the temperature at which the carbonylation is performed is less than 1 15°C

Inventors: TOOZE ROBERT PAUL, TOOZE, ROBERT, PAUL
Applicants: ICI PLC, TOOZE ROBERT PAUL, IMPERIAL CHEMICAL INDUSTRIES PLC, TOOZE, ROBERT, PAUL
Application year: 1994
Main classification: C07C67
IPC codes: B01J31, C07B61, C07C67, C07C69